The latest Windows 10 cumulative update borks searching and causes cortana to use a large amount of CPU in the background (hitting the Windows key and starting to type presents an empty grey box and finds nothing). The issue was apparently raised by Insiders but Microsoft have released it anyway. I encountered this on the weekend and had to roll the update back. Hopefully Microsoft pull it before it is pushed out to a wider audience and not just those unlucky sods like me who unwisely chose to ‘check for updates’.